Tying sutures in surgical procedures is as old as the first stitch and knot used to close a wound. When stitching wounds, a cable, cord, or other string-like object is passed through both sides of the wound and is tightened down against the wound to close the two sides together. The most common way to tighten down the cord is to tie a knot. This entails forming a loop and passing one of the free ends of the cord through the loop at least once. When the free ends of the cord are pulled away from one another, the knot reduces until there is no more room for reduction. If left alone, the knot could come loose. Therefore, techniques for forming different and varying knots have been established. In each case, the surgeon desires the knot to be tied with a sufficient tying force, referred to herein as a locking state, that, if retained after letting go of the ends of the cord, will form a stitch that holds the wound closed. Therefore, in the process for securing the knot, a second knot can be employed directly over or after the first knot to retain the first knot in the locking state with a desired tying force. As long as the first knot does not move or loosen while the second securing knot is placed, then the locking state of the first knot remains. However, there are various counter-forces working against keeping the first knot within the locking state. These counter-forces include the removal of the original tying force, the physical structure of the compressed suture expanding back to its uncompressed steady state, the bends of the knotted suture expanding back to their un-bent state, expansion or swelling of the wound tissue, and others. As such, once the surgeon places the first knot in the locking state and releases the first knot to tie the second locking knot, there is a great chance that that first knot will unravel and leave the locking state, thereby reducing the force from the desired tying force. Accordingly, when surgical stitching is done by hand, the surgeon is required to keep up the pulling force on the opposing ends of the suture knot throughout the time that the second knot is being considered, tied, and fastened. This is a technique practiced repeatedly by surgeons and requires the surgeon to use their relatively large fingertips. Even with the best skill, however, the first knot routinely leaves the desired locking state after the surgeon has moved from keeping the tying force constant on the first knot.
After much experience with tying surgical knots, a surgeon can tie them with approximately the same tying force, but this approximation is neither consistent nor accurate. For each surgical procedure, it is possible to accurately measure the desired tying force, but there is no way for a surgeon to know with any confidence that his/her hand-tied knot is tied close to or at the desired tying force.
Surgical instruments, such as the Cor-Knot (manufactured by LSI Solutions and as described in U.S. Pat. No. 7,833,237 to Sauer), are used to replace hand tied knots at remotes sites within the body. Such instruments have both benefits and drawbacks.
Drawbacks of such surgical instruments include being limited to use with a single suture and a single crimp and generate significant waste during the suture tying process, which waste must be accounted for because there exists the possibility that the waste could be lost within the patient during surgery if safeguards are not taken. In this system “the Cor-Knot system”, a single suture crimp is loaded into the end effector and is secured for a single crimp use. To load the crimp and the snare that passes the suture through the crimp, a loading hook is passed through an end effector. The loading hook has the crimp at its distal end and is attached to a snare loop, which is threaded through the crimp. To secure the crimp between the handle and the snare loop, the snare loop is secured and held outwards as a loop by a teardrop shaped plastic handle. After the hook is threaded into the end effector and the crimp is pressed into the distal end of the end effector, the user must remove the large, plastic handle and dispose of it properly. As such, the action of loading a reload crimp into the device generates a teardrop shaped piece of plastic waste for every single crimp. Care must be taken because there is no positive method of securing the crimp into the ready position within the crimping device. If the crimp becomes dislodged, it may not form a proper securing crimp. This may require the suture to be replaced, which may be extremely difficult. Once the snare loop is used to pull the sutures through the crimp, the snare loop must also be discarded. If during the process of passing the sutures through the crimp the sutures do not fully pass through the crimp, it is possible that the very small crimp could be dislodged from the crimping device and potentially lost within the patient. It would be beneficial to provide a cord-loading device that has minimal or no waste generated during a procedure and that provides multiple securing structures that do not need to be individually loaded during the procedure.
With regard to keeping the locking state of a knot, such instruments are improved over hand-tied knots. First, the distal end of the instrument is much smaller than the tip of the smallest finger of the surgeon, which tip is used to hold down the first knot in the knot-tying process. These instruments allow the surgeon to keep the very small distal end of the instrument pressed against the first knot while they are tying the second knot. In this way, pressure against the first knot is maintained until just before the second knot is clamped down on the first knot. The time while the second knot is not against the first knot leaves a gap that allows the first knot to leave the locking state. It would be beneficial to minimize such a gap and to keep the tying force on the first knot to prevent unwinding or opening of the first knot. As with the surgeon's hands, there is no way for such prior art instruments to know whether the first knot is tied with a force that is close to or at the desired tying force and, especially, is not so much greater to cause harm at the surgical site. Accordingly, it would be beneficial to know, in advance, what is the desired tying force for a particular suture and, during suturing, to know if the suture is being tied and kept at the tying force.
Thus, a need exists to overcome the problems with the prior art systems, designs, and processes as discussed above.